Efforts are currently underway in a number of groups worldwide to develop an implantable retinal prosthesis to restore at least partial sight to persons suffering from certain forms of blindness due to end-stage photoreceptor degenerative diseases such as age-related macular degeneration and hereditary retinitis pigmentosa. See J. D. Weiland et al., “A Biomimetic Retinal Stimulating Array,” IEEE Engineering in Medicine and Biology Magazine, pp. 14-21, September/October 2005 for a recent review of progress in this area. Such retinal prostheses, which are currently being developed, are based on the electronic transfer of visual information from a camera located in front of the eye to receiver electronics which will be implanted within or adjacent to the eye. The receiver electronics will then feed the visual information in pixelized form to an electrode array which is located either directly in front of the retina (epiretinal) or beneath the retinal tissue (sub-retinal). Electrical currents from the electrode array will stimulate neural tissue (e.g. ganglion cells) in the retina to generate a visual perception of spots of light (also termed phosphenes) corresponding to the pixelized visual image, with the goal of being able to restore a measure of sight to a blind person.
Current retinal prosthesis designs that incorporate inner-eye electronics use soft-package techniques to protect the electronics from the corrosive environment of the inner eye. The electronics are typically attached to polymer electrode arrays that have plated platinum electrodes driven via metallized traces. Such devices have a limited operational lifetime of weeks to months, and are also limited in the number of electrodes that can be fabricated using this technology.
What is needed is a hermetic package that will allow a much longer operational lifetime and which can include a much larger number of electrodes up to one thousand or more individually addressable electrodes.
The present invention represents an advance in the art by providing an electrode array for neural stimulation which allows up to one thousand or more individually addressed electrodes to be contained within a two-part ceramic package which can be hermetically sealed. An electronic circuit such as a demultiplexer circuit can be located inside the two-part ceramic package to reduce the number of signal lines needed for operation of the electrode array.
These and other advantages of the present invention will become evident to those skilled in the art.